Toxicological Aspects of Long‐Term Treatment of Keratinocytes with ZnO and TiO2 Nanoparticles

Sunscreens containing ZnO and TiO₂ nanoparticles (NPs) are increasingly applied to skin over long time periods to reduce the risk of skin cancer. However, long‐term toxicological studies of NPs are very sparse. The in vitro toxicity of ZnO and TiO₂ NPs on keratinocytes over short‐ and long‐term applications is reported. The effects studied are intracellular formation of radicals, alterations in cell morphology, mitochondrial activity, and cell‐cycle distribution. Cellular response depends on the type of NP, concentration, and exposure time. ZnO NPs have more pronounced adverse effects on keratinocytes than TiO₂. TiO₂ has no effect on cell viability up to 100 μg mL^?1, whereas ZnO reduces viability above 15 μg mL^?1 after short‐term exposure. Prolonged exposure to ZnO NPs at 10 μg mL^?1 results in decreased mitochondrial activity, loss of normal cell morphology, and disturbances in cell‐cycle distribution. From this point of view TiO₂ has no harmful effect. More nanotubular intercellular structures are observed in keratinocytes exposed to either type of NP than in untreated cells. This observation may indicate cellular transformation from normal to tumor cells due to NP treatment. Transmission electron microscopy images show NPs in vesicles within the cell cytoplasm, particularly in early and late endosomes and amphisomes. Contrary to insoluble TiO₂, partially soluble ZnO stimulates generation of reactive oxygen species to swamp the cell redox defense system thus initiating the death processes, seen also in cell‐cycle distribution and fluorescence imaging. Long‐term exposure to NPs has adverse effects on human keratinocytes in vitro, which indicates a potential health risk.     

RES‐loaded pegylated CS NPs: for efficient ocular delivery

The objective of this study is to develop resveratrol (RES) loaded polyethylene glycols (PEGs) modified chitosan (CS) nanoparticles (NPs) by ionic gelation method for the treatment of glaucoma. While increasing the concentration of PEG, the particle size and polydispersity index of the formulations increased. Entrapment efficiency and RES loading (RL) of NPs decreased while increasing PEG concentration. The in vitro release of NPs showed an initial burst release of RES (45%) followed by controlled release. Osmolality of formulations revealed that the prepared NPs were iso‐osmolar with the tear. Ocular tolerance of the NPs was evaluated using hen''s egg test on the chorioallantoic membrane and it showed that the NPs were non‐irritant. RES‐loaded PEG‐modified CS NPs shows an improved corneal permeation compared with RES dispersion. Fluorescein isothiocyanate loaded CS NPs accumulated on the surface of the cornea but the PEG‐modified CS NPs crossed the cornea and reached retinal choroid. RES‐loaded PEG‐modified CS NPs reduced the intra‐ocular pressure (IOP) by 4.3 ± 0.5 mmHg up to 8 h in normotensive rabbits. These results indicate that the developed NPs have efficient delivery of RES to the ocular tissues and reduce the IOP for the treatment of glaucoma.Inspec keywords: conducting polymers, nanoparticles, nanomedicine, drug delivery systems, particle size, nanofabrication, organic compounds, biomembranes, cellular biophysics, eye, vision defects, biological tissuesOther keywords: RES‐loaded pegylated CS NP, efficient ocular delivery, resveratrol loaded polyethylene glycol modified chitosan nanoparticles, ionic gelation method, glaucoma treatment, particle size, polydispersity index, entrapment efficiency, RES loading, PEG concentration, in vitro release, osmolality formulations, ocular tolerance, hen egg testing, chorioallantoic membrane, improved corneal permeation, RES dispersion, fluorescein isothiocyanate loaded CS NP, cornea surface, reached retinal choroid, intraocular pressure, normotensive rabbits, RES delivery, ocular tissues     

A Chiral‐Nanoassemblies‐Enabled Strategy for Simultaneously Profiling Surface Glycoprotein and MicroRNA in Living Cells

Assemblies of nanomaterials for biological applications in living cells have attracted much attention. Herein, graphene oxide (GO)–gold nanoparticle (Au NP) assemblies are driven by a splint DNA strand, which is designed with two regions at both ends that are complementary with the DNA sequence anchored on the surface of the GO and the Au NPs. In the presence of microRNA (miR)‐21 and epithelial cell‐adhesion molecule (EpCAM), the hybridization of miR‐21 with a molecular probe leads to the separation of 6‐fluorescein‐phosphoramidite‐modified Au NPs from GO, resulting in a decrease in the Raman signal, while EpCAM recognition reduces circular dichroism (CD) signals. The CD signals reverse from negative in original assemblies into positive when reacted with cells, which correlates with two enantiomer geometries. The EpCAM detection has a good linear range of 8.47–74.78 pg mL^?1 and a limit of detection (LOD) of 3.63 pg mL^?1, whereas miR‐21 detection displays an outstanding linear range of 0.07–13.68 amol ng^?1_RNA and LOD of 0.03 amol ng^?1_RNA. All the results are in good agreement with those of the Raman and confocal bioimaging. The strategy opens up an avenue to allow the highly accurate and reliable diagnosis (dual targets) of clinic diseases.     

Mammalian Cells Exhibit a Range of Sensitivities to Silver Nanoparticles that are Partially Explicable by Variations in Antioxidant Defense and Metallothionein Expression

While it is well known that there are interspecies differences in Ag sensitivity, differences in the cytotoxic responses of mammalian cells to silver nanoparticles (Ag NPs) are also observed. In order to explore these response outcomes, six cell lines, including epithelial cells (Caco‐2, NHBE, RLE‐6TN, and BEAS‐2B) and macrophages (RAW 264.7 and THP‐1) of human and rodent origin, are exposed to 20 nm citrate‐ and PVP‐coated Ag NPs with Au cores, as well as 20 nm citrate‐coated particles without cores. An MTS assay shows that while Caco‐2 and NHBE cells are resistant to particles over a 0.1–50 μg mL^?1 dose range, RAW 264.7, THP‐1, RLE‐6TN, and BEAS‐2B cells are more susceptible. While there are small differences in dissolution rates, there are no major differences in the cytotoxic potential of the different particles. However, differences in anti‐oxidant defense and metallothionein expression among different cell types are observed, which can partially explain differential Ag NP sensitivity. So, it is important to consider these differences in understanding the potential heterogeneous effects of nano Ag on mammalian biological systems.     

Development of acetazolamide-loaded,pH-triggered polymeric nanoparticulate in situ gel for sustained ocular delivery: in vitro. ex vivo evaluation and pharmacodynamic study

The objective of research was to develop a novel pH-triggered polymeric nanoparticulate in situ gel (NP-ISG) for ophthalmic delivery of acetazolamide (ACZ) to enhance the conjunctival permeation and precorneal residence time of the formulation by overcoming the limitations of protective ocular barriers. Nanoparticles (NP1--NP12) were developed by nanoprecipitation method and evaluated for pharmacotechnical characteristics including transmission electron microscopy. The optimized formulation, NP10 was dispersed in carbopol 934?P to form nanoparticulate in situ gels (NP-ISG1--NP-ISG5). NP-ISG5 was selected as optimized formulation on the basis of gelation ability and residence time. Ex vivo transcorneal permeation study exhibited significantly higher ACZ permeation from NP-ISG5 (74.50?±?2.20?mg/cm²) and NP10 (93.5?±?2.25?mg/cm²) than eye drops (20.08?±?3.12?mg/cm²) and ACZ suspension (16.03?±?2.14). Modified Draize test with zero score indicated nonirritant property of NP-ISG5. Corneal toxicity study revealed no visual signs of tissue damage. Further, NP-ISG5 when tested for hypotensive effect on intraocular pressure (IOP) in rabbits revealed that NP-ISG5 caused significant decrease in IOP (p?in vitro efficacy, safety and patient compliance.     

DNA‐Assembled Core‐Satellite Upconverting‐Metal–Organic Framework Nanoparticle Superstructures for Efficient Photodynamic Therapy

DNA‐mediated assembly of core–satellite structures composed of Zr(IV)‐based porphyrinic metal‐organic framework (MOF) and NaYF₄,Yb,Er upconverting nanoparticles (UCNPs) for photodynamic therapy (PDT) is reported. MOF NPs generate singlet oxygen (¹O₂) upon photoirradiation with visible light without the need for additional small molecule, diffusional photosensitizers such as porphyrins. Using DNA as a templating agent, well‐defined MOF–UCNP clusters are produced where UCNPs are spatially organized around a centrally located MOF NP. Under NIR irradiation, visible light emitted from the UCNPs is absorbed by the core MOF NP to produce ¹O₂ at significantly greater amounts than what can be produced from simply mixing UCNPs and MOF NPs. The MOF–UCNP core–satellite superstructures also induce strong cell cytotoxicity against cancer cells, which are further enhanced by attaching epidermal growth factor receptor targeting affibodies to the PDT clusters, highlighting their promise as theranostic photodynamic agents.     

High‐Resolution 3D NIR‐II Photoacoustic Imaging of Cerebral and Tumor Vasculatures Using Conjugated Polymer Nanoparticles as Contrast Agent

Exogenous contrast‐agent‐assisted NIR‐II optical‐resolution photoacoustic microscopy imaging (ORPAMI) holds promise to decipher wide‐field 3D biological structures with deep penetration, large signal‐to‐background ratio (SBR), and high maximum imaging depth to depth resolution ratio. Herein, NIR‐II conjugated polymer nanoparticle (CP NP) assisted ORPAMI is reported for pinpointing cerebral and tumor vasculatures. The CP NPs exhibit a large extinction coefficient of 48.1 L g^?1 at the absorption maximum of 1161 nm, with an ultrahigh PA sensitivity up to 2 µg mL^?1. 3D ORPAMI of wide‐field mice ear allows clear visualization of regular vasculatures with a resolution of 19.2 µm and an SBR of 29.3 dB at the maximal imaging depth of 539 µm. The margin of ear tumor composed of torsional dense vessels among surrounding normal regular vessels can be clearly delineated via 3D angiography. In addition, 3D whole‐cortex cerebral vasculatures with large imaging area (48 mm²), good resolution (25.4 µm), and high SBR (22.3 dB) at a depth up to 1001 µm are clearly resolved through the intact skull. These results are superior to the recently reported 3D NIR‐II fluorescence confocal vascular imaging, which opens up new opportunities for NIR‐II CP‐NP‐assisted ORPAMI in various biomedical applications.     

Formulation and corneal permeation of ketorolac tromethamine-loaded chitosan nanoparticles

Abstract

The aim of this work was to formulate chitosan (CS)-based nanoparticles (NPs) loaded with ketorolac tromethamine (KT) intended for topical ocular delivery. NPs were prepared using ionic gelation method incorporating tri-polyphosphate (TPP) as cross-linker. Following the preparation, the composition of the system was optimized in terms of their particle size, zeta potential, entrapment efficiency (EE) and morphology, as well as performing structural characterization studies using Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The data suggested that the size of the NPs was affected by CS/TPP ratio where the diameter of the NPs ranged from 108.0?±?2.4?nm to 257.2?±?18.6?nm. A correlation between drug EE and the corresponding drug concentration added to the formulation was observed, where the EE of the NPs increased with increasing drug concentration, for up to 10?mg/mL. FT-IR and DSC revealed that KT was dispersed within the NPs where the phosphate groups of TPP were associated with the ammonium groups of CS. The in vitro release profile of KT from CS NPs showed significant differences (p?<?0.05) compared to KT solution. Furthermore, mucoadhesion studies revealed adhesive properties of the formulated NPs. The KT-loaded NPs were found to be stable when stored at different storage conditions for a period of 3 months. The ex vivo corneal permeation studies performed on excised porcine eye balls confirmed the ability of NPs in retaining the drug on the eye surface for a relatively longer time. These results demonstrate the potential of CS-based NPs for the ocular delivery of KT.     

Engineered Multifunctional Albumin‐Decorated Porous Silicon Nanoparticles for FcRn Translocation of Insulin

The last decade has seen remarkable advances in the development of drug delivery systems as alternative to parenteral injection‐based delivery of insulin. Neonatal Fc receptor (FcRn)‐mediated transcytosis has been recently proposed as a strategy to increase the transport of drugs across the intestinal epithelium. FcRn‐targeted nanoparticles (NPs) could hijack the FcRn transcytotic pathway and cross the epithelial cell layer. In this study, a novel nanoparticulate system for insulin delivery based on porous silicon NPs is proposed. After surface conjugation with albumin and loading with insulin, the NPs are encapsulated into a pH‐responsive polymeric particle by nanoprecipitation. The developed NP formulation shows controlled size and homogeneous size distribution. Transmission electron microscopy (TEM) images show successful encapsulation of the NPs into pH‐sensitive polymeric particles. No insulin release is detected at acidic conditions, but a controlled release profile is observed at intestinal pH. Toxicity studies show high compatibility of the NPs with intestinal cells. In vitro insulin permeation across the intestinal epithelium shows approximately fivefold increase when insulin is loaded into FcRn‐targeted NPs. Overall, these FcRn‐targeted NPs offer a toolbox in the development of targeted therapies for oral delivery of insulin.     

Nanoparticle‐Enhanced Silver‐Nanowire Plasmonic Electrodes for High‐Performance Organic Optoelectronic Devices

Improved performance in plasmonic organic solar cells (OSCs) and organic light‐emitting diodes (OLEDs) via strong plasmon‐coupling effects generated by aligned silver nanowire (AgNW) transparent electrodes decorated with core–shell silver–silica nanoparticles (Ag@SiO₂NPs) is demonstrated. NP‐enhanced plasmonic AgNW (Ag@SiO₂NP–AgNW) electrodes enable substantially enhanced radiative emission and light absorption efficiency due to strong hybridized plasmon coupling between localized surface plasmons (LSPs) and propagating surface plasmon polaritons (SPPs) modes, which leads to improved device performance in organic optoelectronic devices (OODs). The discrete dipole approximation (DDA) calculation of the electric field verifies a strongly enhanced plasmon‐coupling effect caused by decorating core–shell Ag@SiO₂NPs onto the AgNWs. Notably, an electroluminescence efficiency of 25.33 cd A^?1 (at 3.2 V) and a power efficiency of 25.14 lm W^?1 (3.0 V) in OLEDs, as well as a power conversion efficiency (PCE) value of 9.19% in OSCs are achieved using hybrid Ag@SiO₂NP–AgNW films. These are the highest values reported to date for optoelectronic devices based on AgNW electrodes. This work provides a new design platform to fabricate high‐performance OODs, which can be further explored in various plasmonic and optoelectronic devices.     

Biocompatible Conjugated Polymer Nanoparticles for Efficient Photothermal Tumor Therapy

Conjugated polymers (CPs) with strong near‐infrared (NIR) absorption and high heat conversion efficiency have emerged as a new generation of photothermal therapy (PTT) agents for cancer therapy. An efficient strategy to design NIR absorbing CPs with good water dispersibility is essential to achieve excellent therapeutic effect. In this work, poly[9,9‐bis(4‐(2‐ethylhexyl)phenyl)fluorene‐alt‐co‐6,7‐bis(4‐(hexyloxy)phenyl)‐4,9‐di(thiophen‐2‐yl)‐thiadiazoloquinoxaline] (PFTTQ) is synthesized through the combination of donor–acceptor moieties by Suzuki polymerization. PFTTQ nanoparticles (NPs) are fabricated through a precipitation approach using 1,2‐distearoyl‐ sn ‐glycero‐3‐phosphoethanolamine‐N‐[methoxy(polyethylene glycol)‐2000] (DSPE‐PEG₂₀₀₀) as the encapsulation matrix. Due to the large NIR absorption coefficient (3.6 L g^‐1 cm^‐1), the temperature of PFTTQ NP suspension (0.5 mg/mL) could be rapidly increased to more than 50 °C upon continuous 808 nm laser irradiation (0.75 W/cm²) for 5 min. The PFTTQ NPs show good biocompatibility to both MDA‐MB‐231 cells and Hela cells at 400 μg/mL of NPs, while upon laser irradiation, effective cancer cell killing is observed at a NP concentration of 50 μg/mL. Moreover, PFTTQ NPs could efficiently ablate tumor in in vivo study using a Hela tumor mouse model. Considering the large amount of NIR absorbing CPs available, the general encapsulation strategy will enable the development of more efficient PTT agents for cancer or tumor therapy.     

Multiplexed Molecular Imaging of Fresh Tissue Surfaces Enabled by Convection‐Enhanced Topical Staining with SERS‐Coded Nanoparticles

There is a need for intraoperative imaging technologies to guide breast‐conserving surgeries and to reduce the high rates of re‐excision for patients in which residual tumor is found at the surgical margins during postoperative pathology analyses. Feasibility studies have shown that utilizing topically applied surface‐enhanced Raman scattering (SERS) nanoparticles (NPs), in conjunction with the ratiometric imaging of targeted versus untargeted NPs, enables the rapid visualization of multiple cell‐surface biomarkers of cancer that are overexpressed at the surfaces of freshly excised breast tissues. In order to reliably and rapidly perform multiplexed Raman‐encoded molecular imaging of large numbers of biomarkers (with five or more NP flavors), an enhanced staining method has been developed in which tissue surfaces are cyclically dipped into an NP‐staining solution and subjected to high‐frequency mechanical vibration. This dipping and mechanical vibration (DMV) method promotes the convection of the SERS NPs at fresh tissue surfaces, which accelerates their binding to their respective biomarker targets. By utilizing a custom‐developed device for automated DMV staining, this study demonstrates the ability to simultaneously image four cell‐surface biomarkers of cancer at the surfaces of fresh human breast tissues with a mixture of five flavors of SERS NPs (four targeted and one untargeted control) topically applied for 5 min and imaged at a spatial resolution of 0.5 mm and a raster‐scanned imaging rate of >5 cm² min^?1.     

Formation of a Monolayer Protein Corona around Polystyrene Nanoparticles and Implications for Nanoparticle Agglomeration

Nanoparticle (NP) interactions with cells and organisms are mediated by a biomolecular adsorption layer, the so‐called “protein corona.” An in‐depth understanding of the corona is a prerequisite to successful and safe application of NPs in biology and medicine. In this work, earlier in situ investigations on small NPs are extended to large polystyrene (PS) NPs of up to 100 nm diameter, using human transferrin (Tf) and human serum albumin (HSA) as model proteins. Direct NP sizing experiments reveal a reversibly bound monolayer protein shell (under saturating conditions) on hydrophilic, carboxyl‐functionalized (PS‐COOH) NPs, as was earlier observed for much smaller NPs. In contrast, protein binding on hydrophobic, sulfated (PS‐OSO₃H) NPs in solvent of low ionic strength is completely irreversible; nevertheless, the thickness of the observed protein corona again corresponds to a protein monolayer. Under conditions of reduced charge repulsion (higher ionic strength), the NPs are colloidally unstable and form large clusters below a certain protein–NP stoichiometric ratio, indicating that the adsorbed proteins induce NP agglomeration. This comprehensive characterization of the persistent protein corona on PS‐OSO₃H NPs by nanoparticle sizing and quantitative fluorescence microscopy/nanoscopy reveals mechanistic aspects of molecular interactions occurring during exposure of NPs to biofluids.     

Mesoporous Silica Supported Silver–Bismuth Nanoparticles as Photothermal Agents for Skin Infection Synergistic Antibacterial Therapy

The emergence of multidrug resistant bacteria has resulted in plenty of stubborn nosocomial infections and severely threatens human health. Developing novel bactericide and therapeutic strategy is urgently needed. Herein, mesoporous silica supported silver–bismuth nanoparticles (Ag‐Bi@SiO₂ NPs) are constructed for synergistic antibacterial therapy. In vitro experiments indicate that the hyperthermia originating from Bi NPs can disrupt cell integrity and accelerate the Ag ions release, further exhibiting an excellent antibacterial performance toward methicillin‐resistant Staphylococcus aureus (MRSA). Besides, under laser irradiation, Ag‐Bi@SiO₂ NPs at 100 µg mL^?1 can effectively obliterate mature MRSA biofilm and cause a 69.5% decrease in the biomass, showing a better therapeutic effect than Bi@SiO₂ NPs with laser (26.8%) or Ag‐Bi@SiO₂ NPs without laser treatment (30.8%) groups. More importantly, in vivo results confirm that ≈95.4% of bacteria in abscess are killed and the abscess ablation is accelerated using the Ag‐Bi@SiO₂ NPs antibacterial platform. Therefore, Ag‐Bi@SiO₂ NPs with photothermal‐enhanced antibacterial activity are a potential nano‐antibacterial agent for the treatment of skin infections.     

Self‐Assembled Large Au Nanoparticle Arrays with Regular Hot Spots for SERS

The cost‐effective self‐assembly of 80 nm Au nanoparticles (NPs) into large‐domain, hexagonally close‐packed arrays for high‐sensitivity and high‐fidelity surface‐enhanced Raman spectroscopy (SERS) is demonstrated. These arrays exhibit specific optical resonances due to strong interparticle coupling, which are well reproduced by finite‐difference time‐domain (FDTD) simulations. The gaps between NPs form a regular lattice of hot spots that enable a large amplification of both photoluminescence and Raman signals. At smaller wavelengths the hot spots are extended away from the minimum‐gap positions, which allows SERS of larger analytes that do not fit into small gaps. Using CdSe quantum dots (QDs) a 3–5 times larger photoluminescence enhancement than previously reported is experimentally demonstrated and an unambiguous estimate of the electromagnetic SERS enhancement factor of ≈10⁴ is obtained by direct scanning electron microscopy imaging of QDs responsible for the Raman signal. Much stronger enhancement of ≈10⁸ is obtained at larger wavelengths for benzenethiol molecules penetrating the NP gaps.     

Nanoparticle–Plant Interactions: Two‐Way Traffic

In this Review, an effort is made to discuss the most recent progress and future trend in the two‐way traffic of the interactions between plants and nanoparticles (NPs). One way is the use of plants to synthesize NPs in an environmentally benign manner with a focus on the mechanism and optimization of the synthesis. Another way is the effects of synthetic NPs on plant fate with a focus on the transport mechanisms of NPs within plants as well as NP‐mediated seed germination and plant development. When NPs are in soil, they can be adsorbed at the root surface, followed by their uptake and inter/intracellular movement in the plant tissues. NPs may also be taken up by foliage under aerial deposition, largely through stomata, trichomes, and cuticles, but the exact mode of NP entry into plants is not well documented. The NP–plant interactions may lead to inhibitory or stimulatory effects on seed germination and plant development, depending on NP compositions, concentrations, and plant species. In numerous cases, radiation‐absorbing efficiency, CO₂ assimilation capacity, and delay of chloroplast aging have been reported in the plant response to NP treatments, although the mechanisms involved in these processes remain to be studied.     

Detection of β‐Amyloid by Sialic Acid Coated Bovine Serum Albumin Magnetic Nanoparticles in a Mouse Model of Alzheimer's Disease

The accumulation and formation of β‐amyloid (Aβ) plaques in the brain are distinctive pathological hallmarks of Alzheimer's disease (AD). Designing nanoparticle (NP) contrast agents capable of binding with Aβ highly selectively can potentially facilitate early detection of AD. However, a significant obstacle is the blood brain barrier (BBB), which can preclude the entrance of NPs into the brain for Aβ binding. In this work, bovine serum albumin (BSA) coated NPs are decorated with sialic acid (NP‐BSA_x‐Sia) to overcome the challenges in Aβ imaging in vivo. The NP‐BSA_x‐Sia is biocompatible with high magnetic relaxivities, suggesting that they are suitable contrast agents for magnetic resonance imaging (MRI). The NP‐BSA_x‐Sia binds with Aβ in a sialic acid dependent manner with high selectivities toward Aβ deposited on brains and cross the BBB in an in vitro model. The abilities of these NPs to detect Aβ in vivo in human AD transgenic mice by MRI are evaluated without the need to coinject mannitol to increase BBB permeability. T₂*‐weighted MRI shows that Aβ plaques in mouse brains can be detected as aided by NP‐BSA_x‐Sia, which is confirmed by histological analysis. Thus, NP‐BSA_x‐Sia is a promising new tool for noninvasive in vivo detection of Aβ plaques.     

Effects of Ceria Nanoparticles and CeCl3 on Plant Growth,Biological and Physiological Parameters,and Nutritional Value of Soil Grown Common Bean (Phaseolus vulgaris)

The release of metal ions may play an important role in toxicity of metal‐based nanoparticles. In this report, a life cycle study is carried out in a greenhouse, to compare the effects of ceria nanoparticles (NPs) and Ce³⁺ ions at 0, 50, 100, and 200 mg Ce kg^?1 on plant growth, biological and physiological parameters, and nutritional value of soil‐grown common bean plants. Ceria NPs have a tendency to negatively affect photosynthesis, but the effect is not statistically significant. Ce³⁺ ionic treatments at 50, 100, and 200 mg Ce kg^?1 result in increases of 1.25‐, 0.66‐, and 1.20‐fold in stomatal conductance, respectively, relative to control plants. Both ceria NPs and Ce³⁺ ions disturb the homeostasis of antioxidant defense system in the plants, but only 200 mg Ce kg^?1 ceria NPs significantly induce lipid peroxidation in the roots. Ceria NP treatments tend to reduced fresh weight and to increase mineral contents of the green pods, but have no effect on the organic nutrient contents. On the contrary, Ce³⁺ ion treatments modify the organic compositions and thus alter the nutritional quality and flavor of the green pods. These results suggest that the two Ce forms may have different mechanisms on common bean plants.     

Characterizing the Lateral Friction of Nanoparticles on On‐Chip Integrated Black Lipid Membranes

The use of nanoparticles (NPs) in biomedical applications creates a need for appropriate model systems to systematically investigate NP–membrane interactions under well‐defined conditions. Black lipid membranes (BLMs) are free‐floating membranes with defined composition that are ideally suited for characterizing NP–membrane interactions free of any potential perturbation through a supporting substrate. Herein, arrays of microfabricated BLMs are integrated into a chip‐based platform that is compatible with high‐speed optical NP tracking. This system is used to investigate the lateral diffusion of 40 nm gold spheres tethered to biotinylated lipids through antibody‐functionalized ligands (single‐stranded DNA or polyethylene glycol). Although the NPs show an almost free and ergodic diffusion, their lateral motion is subject to substantial drag at the membrane surface, which leads to systematically smaller diffusion coefficients than those obtained for lipids in the membrane through fluorescence recovery after photobleaching. The lateral mobility of the NPs is influenced by the chemical composition and salt concentration at the NP‐membrane interface, but is independent of the ligand density in the membrane. Together with the observation that nanoprisms, which have a larger relative contact area with the membrane than spherical NPs, show an even slower diffusion, these findings indicate that the lateral mobility of NPs tethered in close vicinity to a membrane is significantly reduced by the friction at the NP‐membrane interface.